The present invention relates generally to support fixtures and more specifically to compliant locking support fixtures.
Support fixtures for propping up workpieces have been widely used in the production of contoured parts from such varying applications as aircraft manufacturing and circuit board manufacturing. Regardless of the workpiece, it is important to be able to hold the piece so that machining or further treatment operations can be performed. Generally, support fixtures for holding articles comprise a device containing vertically disposed adjustable pins or rods and means for securing the pins at a given vertical location. Exemplary support fixtures are described in U.S. Pat. No. 4,200,272 to Godding, U.S. Pat. No. 4,684,113 to Douglas et al., U.S. Pat. No. 5,722,646 to Soderberg et al., and U.S. Pat. No. 5,984,293 to Abrahamson et al.
U.S. Pat. No. 4,200,272 to Godding discloses a work holder comprising a flat horizontal table in which is mounted a two-dimensional array of vertically disposed spaced-apart rods which protrude upwards through the surface. The rods can be moved upwards individually, either manually or by springs or by fluid pressure means such as rams, and then clamped in position so that their tips form a cradle conforming to the shape of the workpiece, in which the workpiece rests.
U.S. Pat. No. 4,684,113 to Douglas et al. discloses a holding fixture which has a contoured holding surface. The fixture includes a plurality of workpiece engaging rods which are individually adjustable in height. A holding force is generated through the rods to hold the workpiece to the fixture.
U.S. Pat. No. 5,722,646 to Soderberg et al. discloses a tooling system having a support table with multiple openings adapted to removably accept a self-contained actuator. Each opening of the support table provides vacuum and air supply lines as well as a bus interface so that each position may be uniquely addressed and commanded separately from any other openings. The self-contained actuator has corresponding connectors for receiving the vacuum and air supply as well as for interfacing with the bus. An actuator may be placed at a particular location by insertion into the receptacle at the opening in the support table aperture. The actuator may be commanded to raise, lower, lock in position and supply vacuum separate from any other actuator.
U.S. Pat. No. 5,984,293 to Abrahamson et al. discloses a fixture for holding printed circuit board assemblies during stencil printing, pick-and-place processing, and other PCB assembly processes. The fixture has a base and a plurality of support members movably attached to the base. The support members may project away from the base along support paths, and the support members are selectively positionable along the support paths when the support members engage a side of a printed circuit board assembly. The support members may be selectively positioned at heights corresponding to a topography of the side of the printed circuit board assembly to uniformly support the printed circuit board assembly.
Some problems with the prior art support fixtures include substantial setup time, the need for operator intervention, and the requirement of expensive or sophisticated controls. A support fixture is desired which is inexpensive and simple to employ and significantly reduces set-up time and operator intervention.
One aspect of the present invention is a pin locking apparatus for use in a support fixture. The pin locking apparatus includes a locking plate having a pin receiving hole and a ball receiving hole, and a ball contained within the ball receiving hole. The bottom of the ball receiving hole merges with a lower portion of the pin receiving hole. The pin locking apparatus has a locking position wherein the ball is positioned approximately at a bottom of the ball receiving hole, and an unlocking position wherein the ball is remote from the bottom of the ball receiving hole.
Another aspect of the invention is a pin locking module for use in a supporting device. The pin locking module includes an enclosure having a pin receiving hole, a pin locking plate contained within a top of the enclosure and including a pin receiving hole and a ball receiving hole, a piston assembly having a piston and a pin, and a ball which is movably contained within the ball receiving hole. The supporting device for holding the pin locking modules includes a grid plate and a base plate, the grid plate having pin locking module receiving holes, an air channel and an air portal, the base plate having an air channel, a plurality of air holes and an air portal.
A further aspect of the invention is a pin locking apparatus for use in a supporting device, having a pin locking plate with a plurality of pin receiving holes and a plurality of ball receiving holes, and a plurality of balls movably held within the ball receiving holes. The supporting device, according to another aspect of the invention, includes a base plate, a cylinder block having a plurality of piston receiving holes, the pin locking plate, a top plate having pin receiving holes, a plurality of balls contained within the ball receiving holes of the pin locking plate, a plurality of piston assemblies slidably mounted within the piston receiving holes, at least one air pressure channel fluidly connected to the pin receiving holes of the cylinder block, and at least one air conduit fluidly connected to the ball receiving holes of the pin locking plate.
Another supporting device according to the present invention includes a base plate, a plurality of support posts mounted to the base plate, a pin locking plate mounted to the support posts and having a plurality of pin receiving holes and ball receiving holes, a top plate mounted to the pin locking plate and having pin receiving holes, a plurality of balls movably contained within respective ones of the ball receiving holes of the pin locking plate, and a plurality of piston assemblies slidably mounted within the pin receiving holes of the pin locking plate and top plate.
A method for positioning a pin according to the present invention includes the steps of lifting a ball contained within a ball receiving hole of a locking plate towards a top of the ball receiving hole, adjusting a pin slidably engaged within a pin receiving hole of the locking plate to a desired position, the pin receiving hole being positioned adjacent to the ball receiving hole, moving the ball towards a bottom of the ball receiving hole so as to contact the ball to the pin, and locking the pin in a locking position with the ball.